Process for forming stencil-sheets.



UNITED STATES PATENT OFFICE.

OUIS E- I UI LER, OF NEW YORK, N. Y., ASSIGNORQBY MESNE ASSIGNMENTS, T0

A. B. DICK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PROCESS FOR FORMING STENCIL-SHEETS.

N0 Drawing.

7 '0 all whom it may concern:

Be it known that I, LOUIS E. FULLER, a citizen of the United States, and a resident of the city of New York, in the county and State of New York, have invented certain new and useful Improvements in Processes,

for Forming Stencil-Sheets, of which the following is a full and COmPlGiLGdISClOSHIG.

My invention relates to sheets coated on impregnated with suitable substances normally impervious to ink, but adapted when struck or impressed by the characters of a typewriter, or similar device, to permit the passage of ink wherever the sheet has been struck or impressed, and thus enable the sheet to be used as a stencil for the reproduction of the characters impressed thereon.

Heretofore it has been the usual custom to form stencil sheets by coating a suitable paper with an impervious coating of wax or.

similar substance, and to form the necessary characters in or on the sheet by striking the wax coat with the characters of an ordinary typewriter, the intention being to express the wax from the sheet wherever it is struck by the character or characters, and thus enable the sheet to be used as a stencil. This method of forming stencils has, however, proved unsatisfactory, because with such sheets it is necessary to remove the wax in order-to secure clear and uniform copies, and this is not possible with an ordinary typewriter or any impression device available for such use. This method is also unsatisfactory, because the wax on the stencil sheets deteriorates under ordinary changes of temperature, and the sheets have a comparati'vely short life.

The object of my improved process is to overcome these difficulties and defects, to. produce a sheet the coating of which is not subject to temperature changes, and which Specification of Letters Patent. I Patented June 23, 1914- Application filed July 0, 1910. Serial No. 572,928.

moisture, to swell or expand, so as to produce a coating having a cellular structure, which when struck or impressed with the desired characters. and dried, will produce smooth and sightly copies, even though the material has not been cut out by the impression character. A suitable composition for this purpose may be formed by -mixing a protein, such as gelatin, with a coagulating agent, such as potassium dichromate and a tempering agent, such as glycerin or sugar, or a mixture of the two. One method for forming this coating is as follows: I first prepare a concentrated solution of gelatin, sugar, acetic acid and water. The proportions of these ingredients may be reasonably varied, with the result that the compound will be thicker or thinner. The solution which I have found to be the best and most useful is as follows: gelatin one part; white sugar, one part; glacial acetic acid pure, one part; glycerin, two parts; water, two parts; all by weight; potassium dichromate in crystals enough to color the compound a. deep yellow. The gelatin should first be broken into pieces of a convenient size and dissolved in the acetic acid and water, a gentle heat, such as a water bath, being applied, if it is desirableto effect solution in a shorter period of time: The sugar and glycerin are then added and the whole thoroughly mixed, so that the ingredients are completely blended and dissolved. The potassium dichromate, preferably powdered crystals, is then added to the extent of as much as the solution will dissolve, or at least enough to color thecompound a deep yellow. The whole is then filtered b suitable means. The solution may be applied to the paper by laying the sheet on a smooth non-absorptive surface, as a plate of glass, and flowing the solution thereover by means of a brush, .a dim light being desirable, in this coating operation as in the operation of preparing the solution as above described. The sheet is then suspended to dry, and when dried it is exposed to daylight or other suitable light. Within a shorter or longer time, dependent upon the intensity of the light, the sheet will change in color to a grayish green or lavender, such change being due to the reduction of potassium dichromate to chrome alum and coagulation of the gelatin. By such exposure and reduction, the compound is rendered non-plastic and substantially into the composition as such.

soluble in water, hot or cold exce t that it will soften slightl under t e in uence of moisture and is hygroscopic. It is also rendered proof against all neutral solvents and against concentrated alkaline anddilute acid solutions. It is also proof against oils and greases, and all solvents of the same.

The foregoing compos'tion is that described in my pending application Serial No. 540,078, and I make no claim herein It may be varied in the manner specified in my said application, and other equivalent compositions may be used in carrying out my present process. In carrying out my process, after the sheet has been dried as above described, it ,is subjected to moisture by being stored in a humidor, or-in any suitable manner, and the moisture swells or expand the coating .on the sheet, so that it assumes a cellular I structure, and yet is impervious to ink. The

sheet is then placed in a typewriter or any suitable impression device, and characters impressed thereon. It, is not necessary to put out the coating, but only to-break down or crush the cellular structure. The sheet is then allowed to' dry, after which it may be placed in a frame and an inked roller passed thereov'er, whereupon the ink vwill pass freely through the portions of the sheet which have been im ressed and reprgdu ce upon an underlying ters which said portions -represent. The softening heretofore mentioned of the-material in the paper is tem orary in the "sense that it is producedfor e particular pur- 08a of formingthe characters, the paper Being practically dry in its ordinary condition; and after bemg. moistened and the. characters comparatively dry,'so that'it may be coni j veniently used iwith a stencil without 'be"--.

and sticky, as it would-be if moistened, while at 'the same the severed edges of the coming limp permanently time drying causes material to shrink and enlarge the" opening.

.-While I have described only "one way of carryingl out my improved rocess, I am aware t at modifications an changes may be made therein by those skilled in the art,

spirit of my invention or the scope of my cla1ms.' 'WhatI'cIaimiSLQ' 1. The process of which cons sts in impregnating a *ing the sheet lank sheet the charac- 1 formed in it, willagain become.-

forming astencil l sheet r s eet'of- 1 aw rendermg said substance normally non softened, by treating the same with a coaguthe sheet so impregnated, 60.

lant and a tempering agent and; dr i th sheet so impregnated, substantially as Y scribed.

3. The process of forming a stencil-sheet which consists in impregnating a sheet of fibrou material with a colloidal substance, rendering said substance normally nonplastic but capable coagulant nated, substantially. as described.

4. The process of forming astencil-sheet of .being temporarily softened, by treating thesame with a'chromic I and drying the sheet so impregwhich consistsin lmpregnating' a sheet of fibrous material with a colloidal substance,

' rendering said substance normally non-plas- 1 tic but capable-of being temporarily softened, by treating the same with a chromic coagulant and a tempering agent and so impregnated, 'substantia ly as described.

5. The process of forming a stencil-sheet. which consists in impregnating a sheet of fibrousmaterial with protein and rendering 9 0 ithezprot in insoluble in water by applying {if-chromite coagulating agent and exposing "itfi'light, substantially as described.

I .6; The process of forming a stencil-sheet which consists in impregnating a sheet of i fibrous material with protein and a -suitable tempering agent, and-rendering the protein 1 'lfinsolublein water by applying a chromic co- 7-.- are. process of ;;'}agula agent and exposing it to light *substdiiti ally as described. 1

forming a stencil-sheet whichconsists in impregbating such sheet,

at a single operation, wit a composition'mcluding a protein, such as gelatin, a chromic coagulating agent I .an exposing the sheet to light to coagulate the coatin' thereon and render it dr but hygroscopic, substantially as describe .e 3- ';;i" r-LOUIS E..;FULLER.

fibrous material with a substance,-

and a tempering agent,

llisclaimer'in' Letters Patent N0. 1 ,101 269;

I p W Y DISCLAIMER; I 1-,\1 0;1,269.'Lottisi1EQ Fuller, New York, N. Y. r Pnoen ss Fon FORLIING STENCIL- l MAonmns. 'Pat'nt dated June 23,1914. Diselaim'er filed December 4, 1916,

Yby the assigneeyA. B. Dick Company.

1 Enters its disclaimer as'follows, to wit: U

1. It disleims anyendyall process er processes 'which include impregnating a" a thin, open,- l.ee'like paper snel fibreussh eet, except such its invelire impregnating as apanese Yosiiinqipaper orits equivalent. V 2. It disclaims any and all process or processes of forming stencil-sheets except such as, employing the said patented inventio'n, are'used, or adapted or intended to be used", for-conversi0n jnt0 stencils by impact or pressure, such, for example, as

I the action-entire type of-e'writing-machine.

" o 'jicii l' Geeette; 2605mm 1-2, 1916 1 1 

